Manufacturing method for fluorine-containing ethane

ABSTRACT

Fluorochromium oxide having a fluorine content of not less than 30 wt. % is used for the fluorination reaction.To provide a manufacturing method for fluorine-containing ethane which contains 1,1,1,2,2-pentafluoroethane as the main component in which the reaction can be performed while controlling the generation of CFCs to the greatest possible extent by fluorinating at least on selected from the group composed of tetrachloroethylene, 2,2-dichloro-1,1,1-trifluoroethane and 2-chloro-1,1,1,2-tetrafluoroethane with hydrogen fluoride.

This application is a 371 of PCT/JP99/03868 filed Jun. 16, 1999.

FIELD OF THE INVENTION

The present invention relates to a manufacturing method forfluorine-containing ethane to obtain 2-chloro-1,1,1,2-tetrafluoroethane(in places abbreviated to HCFC-124) and/or2,2-dichloro-1,1,1-trifluoroethane (in places abbreviated to HCFC-123)as well as 1,1,1,2,2-pentafluoroethane (in places abbreviated toHFC-125) as the main reaction products.

PRIOR ART

HFC 125 is used as a component in an alternative refrigerant gas to1-chloro-1,1-difluoromethane (HCFC-22), because its ozone destructioncoefficient is 0. Among manufacturing methods for HFC-125 using HCFC-124as the material, a manufacturing method using chromium oxide (Cr₂O₃) asthe catalyst is described in publication U.S. Pat. No. 5,475,167 as apaten for controlling the generation of CFCs (which are currency bannedbecause they cause damage to the ozone layer). In the method describedin this publication, a conversion to HCFC-125 of not less than 50% issaid to be necessary. Also, in the method described in the Examples, aCr₂O₃ catalyst with high specific surface area prepared from (N₄)₂Cr₂O₇or one which is further treated with CO, H₂ and H₂O is used. When usingthese catalysts, the amount of CFCs generated is 0.3 mol % of theHFC-125.

Further, in publication U.S. Pat. No. 5,334,787, a manufacturing methodfor HFC-125 through a gas phase reaction from HCF -123 or HCFC-124 isdescribed which uses Cr₂O₃ as the catalyst. According to thisdescription, an increase in the generation rate is necessary in order tocontrol the generation ratio of CFCs to less than 2%. However, there isno detailed description of the actual generation ratio. Similarly inpublication U.S. Pat. No. 5,399,549, a manufacturing method for HFC-125through a gas phase reaction from the same starting material isdescribed which uses Cr₂O₃ as the catalyst. However, there is nodetailed description of the generation ratio of CFCs.

On the other hand, in Japanese Patent Laid-Open No. 247,883/94 amanufacturing method for HFC-125 characterized by a controlled lowamount of CFCs generated is disclosed which uses a catalyst of aluminafluorinated to over 70% in a fluorination reaction of HCFC-123 orHCFC-124. According to this manufacturing method, although the amount ofCFCs generated in the fluorination reaction of HCFC-123 with the aluminacatalyst is 0.5% at a reaction temperature of 350° C., the ratio ofCFCs/HFC-125 is high at about 1.1%.

A fluorination method for tetrachloroethylene with a catalyst offluorinated alumina is described in Japanese Patent Laid-Open No.505,328/91 in which a method is disclosed that use a catalyst of aluminacontaining over 90 wt. % of AlF₃ and carrying metals such as Cr and Mn.This publication, however, includes no description of impurities such asCFCs.

With regard to other methods, although similar methods are alsodisclosed in Japanese Patent Laid-Open No. 247,884/9 and in JapanesePatent Laid-Open No. 97,725/93, the amount of CFCs generated is high inboth of them: the amount of CFCs generated at a reaction temperature350° C. is 1.7% in the former method and 2-3% at a reaction temperatureof 360° C. in the latter method.

Further, the method is disclosed in Japanese Patent Laid-Open No.146,832/89 as a fluorination reaction of tetrachloroethylene using achromium catalyst. The catalyst is Cr₂O₃, prepared by pyrolysis ofammonium dichromate. The amount of CFCs generated, however, is notreferred to at all.

In Japanese Patent Laid-Open No. 268,933/96, a fluorination method oftetrachloroethylene is disclosed that uses a mixed catalyst of MgO andCr₂O₃. Tests were performed with several mixed catalysts havingdifferent ratios of the amount of MgO to Cr₂O₃. When using a catalysthaving a Cr content which minimizes the ratio of CFCs/HFC-125, theconversion rate of tetrachloroethylene is about 93% at a reactiontemperature of 320° C. and the ratio of CFCs/HFC-125 is 2.9%. The amountof CFCs generated itself is lower if the ratio of MgO is higher, whereasthe conversion rate of tetrachloroethylene is lower; it is also shownthat increasing the Cr content in order to obtain a higher conversionrate results in an increase in the amount of CFCs generated by two-foldat a maximum.

OBJECT OF THE INVENTION

The resent invention was carried out in consideration of the abovesituation. The object is to provide a manufacturing method forfluorine-containing ethane in which, when obtaining thefluorine-containing ethane having HFC-125 as the main reaction productthrough a fluorination reaction that uses tetrachloroethylene orHCFC-123 or HCFC-124 as the starting material, generation of CFCby-products can be controlled to be as low as possible by improving thecatalyst used in the fluorination reaction.

CONSTITUTION OF THE INVENTION

The manufacturing method of the present invention for thefluorine-containing ethane that has HFC-125 as the main component byfluorination of at least one selected from the group composed oftetrachloroethylene, HCFC-123 and HCFC-124 with hydrogen fluoride, ischaracterized by using fluorochromium oxide that has not less than 30wt. % of fluorine content as the catalyst.

By increasing the fluorine content of the fluorochromium oxide catalyst,fluorine-containing ethane having HFC-125 as the main component can bemanufactured while controlling the generation of CFC by-products to beas low as possible when applying this catalyst to the fluorinationreaction of the starting material described above. Herein, however, asthe manufactured fluorine-containing ethane, HCFC-123 and/or HCFC-124are usually included in addition to the HFC-125 as described later.

The starting material of the present invention is either a singlematerial selected from tetrachloroethylene, HCFC-12 and HCFC-124 or amixture of two or more of them.

The above HCFC-124 can be obtained by, for example, fluorination ofHCFC-123 or reduction of CFC-114a (2,2-dichloro-1,1,1,2-tetrafluoroethane). The above described HCFC-123 canbe obtained by, for example, fluorination of tetrachloroethylene,chlorination of HCFC-133 (2-chloro-1,1,1-trifluoroethane) or reductionof CFC-113a (1,1,1-trichloro-2,2,2-trifluoroethane). In addition, theabove tetrachloroethylene is manufactured by an industrially commonmethod, e.g. chlorination of hydrocarbon or its chlorine derivatives atits own pyrolysis temperature.

Now even when carrying out a fluorination reaction by HF using theseselected starting materials, the ratio of CFCs/HFC-125 cannot be keptlow by conventional methods. The mechanism of the generation of CFCs asby-products is described as follows.

If the starting material is HCFC-124, the conversion rate to HFC 125cannot reach 100% under ordinary reaction conditions and unreactiveHCFC-124 exists in the reactor. This unreactive HCFC-124 will generateHCFC-123 resulting from the reaction with a by-product, HCl.

On the other hand, if the starting material is HCFC-123, the organicsubstances at the exit of the reactor after the fluorination reactionare mainly fluorinated HCFC-124, HFC-125 tetrachloroethylene chlorinatedby HCl, which is a by-product, and unreactive HCFC-123.

Similarly, if the starting material is tetrachloroethylene, the organicsubstances at the exit of the reactor are mainly HCFC-123, HCFC-124 andHFC-125.

From these gases which passed through the reactor, the gas with HFC-125as the main component is separated and the remaining gas is recycled tothe reactor to improve the yield. This, whatever the starting materialmay be, fluorination of the mixture mainly consisting oftetrachloroethylene, HCFC-123 and HCFC-124 will proceed in the reactoralthough the amount of each is different. Therefore, HCFC-133a andHFC-134a (1,1,1,2-tetrafluoroethane), which are by-products iftetrachloroethylene is the starting material, and CFCs such as CFC-113a,CFC-114a and CFC-115 are generated. CFCs generated in such reactions donot convert to HFC-125 by the fluorination reaction and will be lost inproduction. All of the C C-113a and CFC-114a are fluorinated to CFC-115by recycling the reaction gases. Since the boiling point of CFC-115 isclose to that of HFC-125 and the relative volatility is close to 1,separation is difficult in an ordinary fractionator. Removing theserequires separate facilities for extractive distillation which willincrease costs. Further, CFCs are banned substances as described above,because they destroy the ozone layer, and it is necessary to minimizetheir discharge in order to protect the global environment. For thesereasons, the amounts of CFCs generated including CFC-115 should bereduced as far as possible.

The present inventors have examined earnestly a fluorinaton reaction oftetrachloroethylene, HCFC-123 and HCFC-124 to achieve the presentinvention and have found that the ratio of CFCs/HFC-125 (iftetrachloroethylene is the starting material, the ratio of CFCs to thetotal of HCFC-123, HCFC-124 and HFC-125) is not more than 0.5% whenperforming a fluorination reaction using a fluorochromium oxide catalystin which the content of fluorine is not less than 30 wt. % at a reactiontemperature of 300° C. when tetrachloroethylene is the startingmaterial, is not more than 1.0% when HCFC-123 is the starting material,and is not more than 0.1% when HCFC-124 is the starting material, at areaction temperature of 315° C.

For the chromium oxide necessary for preparation of the catalyst, onewhich is highly active with a specific surface area of not less than 120m²/g is preferable as disclosed in Japanese Patent Laid-Open No.146,680/93. In the present invention, the chromium oxide is furtherfluorinated to have a fluorine content of not less than 30 wt. % ansubmitted to the reaction. Therefore, for example, when charging thechromium oxide (unfluorinated substance) into the reactor, the chromiumoxide can be fluorinated at least at the step immediately before thefluorination reaction of the above starting materials to givefluorochromium oxide.

Fluorination of the chromium oxide may be performed using any knownmethod such as the one described in Japanese Patent Laid-Open No.146,680/93. In order to increase the fluorine content, for example, thechromium oxide may be treated with HF at a high temperature for anextended time. Actually, when the chromium oxide was treated with HF at360° C. for 2 hr, fluorochromium oxide with a fluorine content of 31.4wt. % was obtained.

In the present invention, fluorochromium oxide prepared by a methodother than the above as well as fluorochromium oxide already used as acatalyst in the fluorination reaction of halogenated hydrocarbon can beused as suitable catalysts. Namely, if fluorochromium oxide which has alower fluorine content before the reaction is used over an extended timein the fluorination reaction of halogenated hydrocarbon, it will come tohave a higher fluorine content of not less than 30 wt. % which issuitable for the present invention. Actually, in the experiment wherethe fluorination reaction of HCFC-133a was performed where the molarratio of HF/HCFC-133a was 4 at a reaction temperature of 350° C. for 140hr, fluorochromium oxide which has a fluorine content of 35.2 wt. % wasobtained.

The present inventors have found that it is extremely significant not tosimply fluorinate chromium oxide, but to fluorine it as prepared with afluorine content of not less than 3 wt. %. According to the findings ofthe present inventors, when the fluorination rate (the fluorine content)of chromium oxide has been adjusted to not less than 30 wt. %, theobjective HFC-125 is obtained with high selectivity and generation ofCFCs can be well controlled. The preferred range for the fluorinecontent is between 30 wt. % and 45 wt. %.

In the resent invention, although no specific limits are set on thespecific surface area of the fluorochromium oxide catalyst, the range isusually 25 m²/g−130 m²/g, and preferably 40 m²/g−100 m²/g.

The fluorination reaction of the starting materials with HF in thepresent invention is usually conducted at a reaction temperature of250-400° C., and preferably 280-350° C. If the contact temperature andthe molar ratio are the same the conversion rate to HFC-125 increases asthe reaction temperature becomes higher. However, it is necessary toselect the reaction temperature carefully since it has a large effect onthe amount of by-products generated.

Also the ratio of HF used in the fluorination reaction to the startingmaterial as described above is not specifically limited in the presentinvention. However, the molar ratios of HF to tetrachloroethylene, HF toHCFC-124, and HF to HCFC-123, are usually selected from the range 1.5:1to 15:1 and preferably 2:1 to 9:1. Specifically, it is preferable toconduct the fluorination reaction while increasing the ratio of the HFamount to reduce the amount of CFCs generated, which has thedisadvantage of degrading the economics of the process itself because itincreases the amount of HF recycled. Therefore, taking both conditionsinto consideration, well-balanced individual reaction conditions aremore practical when conducting the fluorination reaction.

In the resent invention, there is no specific limit on the pressure ofthe fluorination reaction of the starting materials, however, sinceseparation of the products and the purfication process are advantageousunder certain pressure conditions, this may be decided based on thesecondition. The range of reaction pressures usually adopted is 0.01MPaG-2.0 MPaG.

In the present invention, the gas containing HFC-125 which is the maincomponent produced by the fluorination reaction the starting material isseparated and recovered once. Thereafter it is desirable to recycle theresidue containing HCFC-123 and/or HCFC-124 back into the reactormultiple times. This is associated with improving the yield of HFC-125and one of the most significant results of this invention 5 thatgeneration of CFCs can be also controlled by this recycling.

When performing the present invention, it is sometimes necessary to payattention to the phenomenon of deterioration of the catalyst over time.

In the event that deterioration of the catalyst becomes particularlyproblematic in the present invention, it is preferable and effective toinclude oxygen of 0.1 mol. % to 16 mol. % in the starting material toeffectively prevent the deterioration.

INDUSTRIAL APPLICATION

In the manufacturing method for fluorine-containing ethane of thepresent invention, fluorine-containing ethane containing HFC-125 as amain component can be manufactured with a large degree of control overthe generation of CFCs because when fluorinating the starting materialsselected, either singly or as a mixture, from the group composed oftetrachloroethylene, HCFC-123 and HCFC-124 with hydrogen fluoride, ahighly specified fluorochromium oxide with a fluorine content of notless than 30 wt. % is used as the catalyst.

EXAMPLE

The following Examples will be given to further illustrated the presentinvention. However, it should be understood that the present inventionis not limited to these Examples.

Example 1

The fluorochromium oxide catalyst was prepared as described below.First, 10% ammonia water was added to 765 g of 5.7% aqueous chromiumnitrate. After the obtained precipitate was filtered and washed, thiswas dried in air at 120° C. for 12 hr to give chromium hydroxide. Thischromium hydroxide was molded to pellets of 3.0 mm in diameter and 3.0mm in height which were calcined at 400° C. for 2 hr in a flow ofnitrogen gas to give chromium oxide.

Next, the chromium oxide was gradually heated to 200° C. −360° C., andwhen it reached 360° C., it was fluorinated with hydrogen fluoride for220 hr to give fluorochromium oxide. The resulting specific surface areaof this fluorochromium oxide by the BET method was 70 m²/g and thefluorine content was 31.4 wt. %.

Subsequently, using this fluorochromium oxide as the catalyst, afluorination reaction of HCFC-124 was performed under the followingconditions: 10 g of the catalyst was used; the flow rate of the HCFC-124was 50 Nml/min; the flow rate of the HF was 100 Nml/min; the W/Fo was 4(g·sec·Nml⁻¹); the molar ratio of HF/HCFC-124 was 4; and the reactiontemperature as 315° C. Then the catalyst was charged in a Hastelloy Creaction tube 15 mm in internal diameter for the reaction. After washingthe reaction gas with water, it was analyzed by gas chromatography usinga Polapack Q column. The results are given in Table 1.

TABLE 1 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 2 315 10.9 33.3 55.6 0.123 0.221 * W: Catalystweight (g), Fo: Gas flow rate converted to standard state (ml/sec).

Example 2

Except that fluorochromium oxide (fluorine content: 35.2 wt. %) used inthe fluorination reaction of HCFC-133a was used, the fluorinationreaction of HCFC-124 was performed under conditions similar toExample 1. The reaction results are given in Table 2.

TABLE 2 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 2 315 10.6 40.4 48.9 0.073 0.150

Example 3

Except that fluorochromium oxide (fluorine content: 41.5 wt. %) used inthe fluorination reaction of HCFC-133a was used, the fluorinationreaction of HCFC-124 was performed under conditions similar toExample 1. The reaction results are given in Table 3.

TABLE 3 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 2 315 10.4 47.4 42.1 0.042 0.099

Comparative Example 1

Except using a catalyst (specific surface area: 140 m²/g, fluorinecontent: 12 wt. %; referred to as a “lower fluorinated catalyst”)obtained under conditions for the fluorination of chromium oxide at 200°C. for 2 hr, the fluorination reaction of HCFC-124 was performed underconditions similar to Example 1. The reaction results are given in Table4.

TABLE 4 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 2 315 11.1 26.0 62.6 0.176 0.281

Example 4

Except setting the flow rate of HCFC-124 to 100 Nml/min, the flow rateof HF to 200 Nml/min, and the W/Fo to 2(g·sec·Nml⁻¹), the fluorinationreaction of HCFC-124 was perform under conditions similar to Example 2.The reaction results, are given in Table 5.

TABLE 5 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 2 2 315 6.7 56.6 36.6 0.037 0.100

Comparative Example 2

Except using a catalyst (fluorine content: 25 wt. %) obtained underconditions for the fluorination of chromium oxide at 360° C. for 155 hr,the fluorination reaction of HCFC-124 as performed under conditionssimilar to Example 1. The reaction results are given in Table 6.

TABLE 6 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 2 315 11.0 28.2 60.3 0.157 0.260

Comparative Example 3

Except using the lower fluorinated catalyst used in Comparative Example1, the fluorination reaction of HCFC-124 was performed under conditionssimilar to Example 4. The reaction results are given in Table 7.

TABLE 7 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 2 2 315 8.2 44.6 47.1 0.081 0.172

Example 5

Except setting the molar ratio of HF/HCFC-124 to 4, the flow rate ofHCFC-124 to 30 Nml/min, and the flow rate of HF to 120 Nml/min, thefluorination reaction of HCFC-124 was performed under conditions similarto Example 2. The reaction results are given in Table 8.

TABLE 8 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 4 315 6.5 40.7 52.7 0.044 0.084

Comparative Example 4

Except using a lower fluorinated catalyst used in Comparative Example 1,the fluorination reaction of HCFC-124 was performed under conditionssimilar to Example 5. The reaction results are given in Table 9.

TABLE 9 HF/ HCFC- Reaction Concentration in Organic CFCs/ 124 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 4 315 6.6 31.0 62.2 0.079 0.128

Example 6

Except setting HCFC-123 as the starting material, the flow rate ofHCFC-123 to 30 Nml/min, the flow rate of HF to 120 Nml/min, the W/Of to4 (g·sec·Nml⁻¹), the molar ratio of HF/HCFC-123 to 4, and the reactiontemperature to 315° C., the fluorination reaction was performed underconditions similar to Example 2. The reaction results are given in Table10.

TABLE 10 HF/ HCFC- Reaction Concentration in Organic CFCs/ 123 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 4 315 35.4 32.9 31.2 0.251 0.806

Comparative Example 5

Except using the lower fluorinated catalyst used in Comparative Example1, the fluorination reaction of HCFC-123 was performed under conditionssimilar to Example 6. The reaction results are given in Table 11.

TABLE 11 HF/ HCFC- Reaction Concentration in Organic CFCs/ 123 Temp-Substances (%) HFC- Molar erature HCFC- HCFC- HFC- 125 W/Fo Ratio (° C.)123 124 125 CFCs (%) 4 4 315 29.1 29.9 40.4 0.432 1.07

Example 7

Using the same catalyst as in Example 2, the fluorination reaction wasperformed using tetrachloroethylene (represented as C₂Cl₄ in the Table)as the starting material. The reaction was performed under the followingconditions: amount of tetrachloroethylene supplied was 0.22 g/min; theflow rate of HF was 270 Nml/min; the molar ratio of HF/tetrachloroethylene was 9; and the W/Fo was 2. The reaction results aregiven in Table 12. Herein, in the reaction of tetrachloroethylene, theratios of CFCs to the total (hereinafter represented as 12X) ofHCFC-123, HCFC-124 and HFC-125 are shown in the Table.

TABLE 12 HF/ Reaction Concentration in Organic C₂Cl₄ Temp- Substances(%) CFCs/ Molar erature HCFC- HCFC- HFC- 12X W/Fo Ratio (° C.) 123 124125 CFCs (%) 2 9 300 22.3 13.6 4.01 0.169 0.423

Comparative Example 6

Except using the same catalyst as used in Comparative Example 1 in thereaction in Example 7, the fluorination reaction of tetrachloroethylenewas performed under conditions similar to Example 7. The reactionresults are given in Table 13.

TABLE 13 HF/ Reaction Concentration in Organic C₂Cl₄ Temp- Substances(%) CFCs/ Molar erature HCFC- HCFC- HFC- 12X W/Fo Ratio (° C.) 123 124125 CFCs (%) 2 9 300 25.1 13.0 2.81 0.271 0.662

Example 8

Except supplying 1 mol % oxygen to tetrachloroethylene in the reactiongas, the fluorination reaction of tetrachloroethylene performed underconditions similar to Example 7. The reaction results are given in Table14. Significant reduction in the catalyst activity due to deteriorationwas not observed even after reaction for 1,000 hr.

TABLE 14 HF/ Reaction Concentration in Organic C₂Cl₄ Temp- Substances(%) CFCs/ Molar erature HCFC- HCFC- HFC- 12X W/Fo Ratio (° C.) 123 124125 CFCs (%) 2 9 300 15.4 6.80 1.22 0.311 1.33

Comparative Example 7

Except using the same catalyst as used in Comparative Example 1 in thereaction in Example 8 the fluorination reaction of tetrachloroethylenewas performed under conditions similar to Example 8. The reactionresults are given in Table 15.

TABLE 15 HF/ Reaction Concentration in Organic C₂Cl₄ Temp- Substances(%) CFCs/ Molar erature HCFC- HCFC- HFC- 12X W/Fo Ratio (° C.) 123 124125 CFCs (%) 2 9 300 16.2 7.49 1.37 0.385 1.54

As shown in each Example, it is understood that if catalyst which fulfilthe present inventive conditions are used for the fluorination reactionsof the starting materials, the generation of CFCs can be fullycontrolled and the objective products can be obtained with goodselectivity even when modifying the reaction conditions and the startingmaterial. To the contrary, as shown in each Comparative Example, singcatalysts out of the present inventive condition will not have asignificant effect on controlling the generation of CFCs.

What is claimed is:
 1. A manufacturing method for fluorine-containingethane characterized by that fluorochromium oxide with a fluorinecontent of not less than 30 wt. % is used as a catalyst whenfluorine-containing ethane which contains 1,1,1,2,2-pentafluoroethane asthe main component is obtained by fluorinating at least one selectedfrom the group consisting of tetrachloroethylene,2,2-dichloro-1,1,1-trifluoroethane and2-chloro-1,1,1,2-tetrafluoroethane with hydrogen fluoride.
 2. Amanufacturing method for fluorine-containing ethane as claimed in claim1 wherein the fluorine content of said fluorochromium oxide catalyst is30-45 wt. %.
 3. A manufacturing method for fluorine-containing ethane asclaimed in claim 1 wherein fluorine-containing ethane also containing2-chloro-1,1,1,2-tetrafluoroethane and/or2,2-dichloro-1,1,1-trifluoroethane as reaction products is obtained. 4.A manufacturing method for fluorine-containing ethane as claim d inclaim 1 wherein 2-chloro-1,1,1,2-tetrafluoroethane and/or2,2-dichloro-1,1,1-trifluoroethane from the reaction mixture are mainlycirculated in said fluorination reaction.
 5. A manufacturing method forfluorine-containing ethane as claimed in claim 1 wherein saidfluorochromium oxide catalyst is prepared by a fluorination reaction ofchromium oxide.
 6. A manufacturing method for fluorine-containing ethaneas claimed in claim 1 wherein the fluorochromium oxide catalystgenerated from the fluorination reaction of halogenated hydrocarbon isused as the said fluorochromium oxide catalyst.